Phenylketonuria or PKU is a rare condition were a baby is born without the enzyme called phenylalanine hydroxylase. This leads to them loosing the ability to properly break down an amino acid called phenylalanine. It was first discovered by the Norwegian physician Ivar Asbjørn Følling in 1934. In , it is known as Følling's Disease. Dr. Følling was one of the first physicians to analyze this disease by taking urine samples of two affected siblings led him to urge other physicians to test other affected patients. The test When not properly treated it can lead to forms of mental retardation, brain damage, impaired social skills and seizures. It is inherited through genetics and both parents must pass on the defective gene for the child to inherit it, also known as autosomal recessive trait.
Physical Symptoms
Molecular Level
Without the enzyme phenylalanine hydroxylase, the body cannot convert the amino acid phenylalanine into the amino acid tyrosine. Since this reaction will not take place, phenylalanine accumulates as tyrosine stays deficient. The buildup of phenylalanine is how it is detected. The phenylalanine buildup found in the blood is diagnostic of PKU. Phenylalanine plays a role in the body's production of melanin, which controls the pigments for skin and hair. This leads to infants afflicted with this disease to have lighter skin or hair coloration. The mental retardation is also caused by the phenylalanine buildup. Phenylalanine is a large neutral amino acid (LNAA). LNAAs compete for transport across the blood-brain barrier, via the large neutral amino acid transporter. Since phenylalanine is in buildup in the blood, it saturates the transporter and causes a buildup which means less of the other LNAAs in the brain. These other amino acids are necessary for proteins required for neural transmitter functions. This leads to problems with brain development, and brain damage or mental retardation. These also block other neural transmitters that control motion in the arms and legs leading to twitching or tremors. The buildup of phenylalanine leads to a musty odor if not treated as well.
Blood Sample Test
Symptoms
Delayed mental and social skills
Head size significantly below normal
Hyperactivity
Jerking movements of arms or legs
Mental Retardation
Seizures
Skin rashes
Tremors
Unusual positioning of the hands
Musty Odor of skin and breathe
Treatment
If discovered in an infant early enough, a controlled diet that manages the phenylalanine in their body can lead to normal brain growth. Medications can also help in managing the levels of phenylalanine in the body along with this diet. This diet is followed for the first sixteen years of a patients life and they must restrict foods high in phenylalanine such as meat, chicken, fish, eggs, nuts, cheese, and cow milk. Starchy foods must also be eaten with care such as potatoes, bread, pasta and corn. Many types of diet food or diet soda must be avoided as well because artificial sweeteners, such as aspartame, contain the amino acids phenylalanine and aspartic acid. Along with diet, medicine, formulas and pills can be added to help reduce levels of phenylalanine in the blood. Oral administration of tetrahydrobiopterin help to reduce the amount of phenylalanine in the blood. This chemical and similar compounds are used for the overall treatment of PKU.
Video Overview
Chances
The chances of a baby contracting PKU are 1 in 15,000 births but vary from location. In Ireland the odds are 1 in 4,500 to 1 and 13,000 births in Norway to 1 in 100,000 in Finland. The most common birthrate is in Turkey, with a 1 in 2,600 chance.
By: Joe Fleischman
Table of Contents
What is Phenylketonuria?
Phenylketonuria or PKU is a rare condition were a baby is born without the enzyme called phenylalanine hydroxylase. This leads to them loosing the ability to properly break down an amino acid called phenylalanine. It was first discovered by the Norwegian physician Ivar Asbjørn Følling in 1934. In , it is known as Følling's Disease. Dr. Følling was one of the first physicians to analyze this disease by taking urine samples of two affected siblings led him to urge other physicians to test other affected patients. The test When not properly treated it can lead to forms of mental retardation, brain damage, impaired social skills and seizures. It is inherited through genetics and both parents must pass on the defective gene for the child to inherit it, also known as autosomal recessive trait.
Without the enzyme phenylalanine hydroxylase, the body cannot convert the amino acid phenylalanine into the amino acid tyrosine. Since this reaction will not take place, phenylalanine accumulates as tyrosine stays deficient. The buildup of phenylalanine is how it is detected. The phenylalanine buildup found in the blood is diagnostic of PKU. Phenylalanine plays a role in the body's production of melanin, which controls the pigments for skin and hair. This leads to infants afflicted with this disease to have lighter skin or hair coloration. The mental retardation is also caused by the phenylalanine buildup. Phenylalanine is a large neutral amino acid (LNAA). LNAAs compete for transport across the blood-brain barrier, via the large neutral amino acid transporter. Since phenylalanine is in buildup in the blood, it saturates the transporter and causes a buildup which means less of the other LNAAs in the brain. These other amino acids are necessary for proteins required for neural transmitter functions. This leads to problems with brain development, and brain damage or mental retardation. These also block other neural transmitters that control motion in the arms and legs leading to twitching or tremors. The buildup of phenylalanine leads to a musty odor if not treated as well.
Symptoms
Treatment
If discovered in an infant early enough, a controlled diet that manages the phenylalanine in their body can lead to normal brain growth. Medications can also help in managing the levels of phenylalanine in the body along with this diet. This diet is followed for the first sixteen years of a patients life and they must restrict foods high in phenylalanine such as meat, chicken, fish, eggs, nuts, cheese, and cow milk. Starchy foods must also be eaten with care such as potatoes, bread, pasta and corn. Many types of diet food or diet soda must be avoided as well because artificial sweeteners, such as aspartame, contain the amino acids phenylalanine and aspartic acid. Along with diet, medicine, formulas and pills can be added to help reduce levels of phenylalanine in the blood. Oral administration of tetrahydrobiopterin help to reduce the amount of phenylalanine in the blood. This chemical and similar compounds are used for the overall treatment of PKU.
Video Overview
Chances
The chances of a baby contracting PKU are 1 in 15,000 births but vary from location. In Ireland the odds are 1 in 4,500 to 1 and 13,000 births in Norway to 1 in 100,000 in Finland. The most common birthrate is in Turkey, with a 1 in 2,600 chance.
Works Cited"Phenylketonuria." Wikipedia, the Free Encyclopedia. Web. 07 Feb. 2011. <http://en.wikipedia.org/wiki/Phenylketonuria>."PubMed Health - Phenylketonuria." Web. 07 Feb. 2011. <http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002150>. "YouTube - PKU." YouTube - Broadcast Yourself. Web. 07 Feb. 2011. <http://www.youtube.com/watch?v=KUJVujhHxPQ>.